This report summarizes clinical frequencies of systemic hypertension and necropsy evidence of cardiomegaly in various cardiovascular conditions termed "the hypertensive diseases" because of their frequent association with systemic hypertension. Although long recognized as a major risk factor, systemic hypertension appears to be an even greater risk factor to development of various cardiovascular conditions than previously appreciated. Hypertension by itself appears to be the sole underlying factor in most cases of non-traumatic cerebral arterial or aortic rupture. In association with hyperlipidemia, hypertension clearly accelerates atherosclerosis and its devastating consequences.